The invention relates to quick disconnect couplings and, more particularly, to a female quick disconnect coupler which provides for quick disconnect and preferably also quick connect.
Quick disconnect couplings are used, for example, to connect hoses in hydraulic fluid lines. A typical application is on agricultural tractors to connect the tractor hydraulic system with attachable implements. The tractor typically includes one or more female coupler sockets, while the implements include one or more male coupler nipples. Pneumatic and other applications for such couplings are also well known.
Over the years changes have occurred in these systems which have required changes and performance improvements in the couplings. One early coupling design is shown in U.S. Pat. No. 4,077,433 where the female coupler includes a valve body slidable within the housing and a poppet valve internal to the valve body. The poppet valve is axially movable to engage a check valve in a male coupler when the male coupler is inserted into the female coupler. When low pressure is present in the male coupler, the poppet valve moves the check valve (ball valve) off its valve seat to allow flow from the female coupler to pass to the male coupler. When higher pressures are present in the male coupler, an internal passage in the poppet valve provides incoming fluid pressure to the rear surface of the poppet valve. Due to the differences in effective surface areas, the fluid pressure assists in driving the poppet valve against the check valve to move the check valve into an open position.
An improvement in this coupling is shown in U.S. Pat. No. 4,598,896, where a separate piston is located around the poppet valve. The piston can engage the poppet valve when moved forwardly. An internal passage in the poppet valve provides fluid pressure to the rear surface of the piston, which assists in driving the poppet valve against the check valve in the male coupler in high pressure situations. A spool is also provided around the piston and poppet valve in this coupling. The spool is fixed to the valve body and includes a port for exhausting pressure within the poppet valve. A retainer sleeve with a seal surrounds the port on the spool, and when the valve body slides within the housing (when the male coupler is inserted or removed), the port relieves the internal pressure in the female coupler to atmosphere.
In some cases, particularly when a pair of couplers are used to direct fluid to and from a hydraulic cylinder in an implement, a check valve mechanism is also provided in the female coupler to prevent the rapid backflow of pressure out of the female coupler when a pressure imbalance occurs within the system, such as during thermal expansion of the fluid caused by severe operating conditions, or when the implement is dragged over an uneven surface. In these situations, one of the female couplers can allow the check valve in an associated male coupler to close, which can cause a block in the system when the flow through the female coupler is desired.
To remedy this problem, some female couplers include a check valve mechanism which allows fluid to flow relatively unimpeded rearwardly to the rear surface of the piston, but which restricts or prevents fluid flow forwardly out of the female coupler. One known check valve mechanism includes a valve ball located within the internal bore of the piston which is spring-biased in both directions to allow fluid to flow rearwardly through the piston at a higher flow rate than forwardly through the piston.
The above couplings have received wide-spread acceptance in the marketplace for providing reliable, serviceable and effective components which operate under a variety of conditions. Some of these couplings direct the fluid internally through the poppet valve to the rear surface of the piston. The flow path includes a radial hole formed in the side of the poppet valve, and a central bore extending axially through the poppet valve. A spring is commonly disposed within the central bore of the poppet valve for biasing the poppet valve against the valve seat. As the spring flexes, the spring can interfere with the flow through the radial hole, which can reduce or even temporarily interrupt the flow through the poppet valve. This can cause an uneven driving force of the piston against the poppet valve, which can be undesirable in certain applications.
Towards providing a direct and uninterrupted flow path to the rear surface of the piston to facilitate moving the poppet valve against the check valve in the male coupler, U.S. Pat. No. 6,016,835 discloses a quick disconnect coupling wherein the female coupler includes a housing adapted to receive a male coupler. The housing includes a valve body slidable within the housing, and a poppet valve internal to the valve body. A piston surrounds the poppet valve to assist in moving the poppet valve against the check valve in the male coupler. Unlike prior female couplers, the flow passage to the rear surface of the piston is provided internally of the piston, rather than the poppet valve, which provides a direct and uninterrupted flow path to the rear surface of the piston to facilitate moving the poppet valve against the check valve in the male coupler. In one design, the flow path extends axially through a tubular main portion of the piston closely surrounding the poppet valve to an internal cavity bounded by an enlarged end portion of the piston, and then to the rear surface of the piston. The flow path can be provided through one or more bores formed axially through the tubular main portion of the poppet valve.
According to second design of quick disconnect coupling disclosed in the ""835 patent, a check valve is provided to prevent fluid rapidly flowing from the female coupler during pressure imbalances in the system. The check valve includes an annular wiper seal supported on the rear surface of the piston, and projecting radially inward therefrom. A poppet guide and relief poppet assembly is provided in the rear end of the valve body and extends axially forward internally of the piston and poppet valve. The poppet guide and relief poppet assembly includes a circumferential ridge along an exterior surface thereof. The wiper seal on the piston seals against the annular ridge on the assembly when the pressure drops in the female coupler and the piston moves forwardly within the coupler body. In this position, the wiper seal, also referred to as a trap seal, allows fluid to pass only rearward through the female coupler to the rear surface of the piston, and prevents a vacuum in the female coupler from allowing the male check valve to close. The fluid pressure behind the wiper seal is relieved to ambient only during connect and disconnect to allow the piston to move rearwardly.
In the past, the trap seal sometimes would be xe2x80x9cblown outxe2x80x9d when a surge of pressurized fluid would pass through the trap seal. This obviously negatively impacts the performance of the coupling and may necessitate repair or replacement of the female coupler.
Other problems have been encountered in female couplers which have an axial end port. Heretofore, a spacer has been used in the housing to provide a flow path for pressurized fluid around the piston and also to isolate the pressurized flow path from a vent port. One end of the spacer is supported by a tubular extension of a housing end plug which is threaded into the end of a cylindrical portion of the housing opposite the flow port. The other end of the sleeve is radially supported in the housing at an annular land including an annular seal which seals against the inner diameter surface of the housing. The annular seal separates high pressure flow from the usually zero pressure in the vent port. The high pressure acting on the seal may cause the seal to be extruded between the spacer and housing.
Still another problem area in prior art female couplers has been contamination of the region containing locking balls that lock the male coupler in the female coupler. Various attempts have been made in the past to prevent sand or other foreign material from entering the locking ball region, but each has had one or more drawbacks associated therewith.
In any case, a constant demand exists in the industry for novel and unique couplings which overcome one or more of the aforesaid problems, and which preferably are reliable, easily serviceable, and operate under a variety of conditions.
The present invention provides improvements in female couplers which overcome one or more of the aforesaid problems encountered with prior art female couplers.
According to one aspect fo the invention, a quick disconnect female coupler comprises a housing and a valve body axially movable in the housing. The valve body has a main cavity and a poppet valve seat at the forward end of the main cavity. A poppet valve is axially movable in the valve body toward and away from the poppet valve seat, and a piston is provided for forwardly urging the poppet valve toward the poppet valve seat upon application of pressurized fluid to the rear side of the piston. A flow passage for supplying pressurized fluid from the main cavity to the back side of the piston has associated therewith a trap seal valve seat and a resilient wiper seal engageable with the trap seal valve seat to block reverse flow of pressurized fluid from behind the piston to the main cavity while permitting flow of pressurized fluid from the main cavity to the rear side of the piston. The wiper seal is retained in a radially opening annular groove and includes at its rear side an annular recess that allows rearward rolling/flaring of the wiper seal in the annular groove when the wiper seal is subjected to a surge of high pressure fluid from the main cavity to the back side of the piston, whereby the wiper seal moves out of the way of the high pressure fluid surge to avoid being forced out of the annular groove.
In a preferred embodiment, the annular recess defines a web joining an annular base portion and an annular sealing portion of the wiper seal, and the wiper seal is radially elongated in cross-section. The annular base portion preferably is larger in cross-section than the annular sealing portion and is retained in the annular groove that preferably is located in a radially inner surface of the poppet valve piston. As will be appreciated, the annular relief preferably functions as a catch for rear side wall of the annular groove when the wiper seal is rotated thereover to aid in holding the wiper seal in the annular groove when a surge of high pressure fluid passes from the main cavity to the back side of the piston.
According to another aspect of the invention, a female coupler comprises a housing having an internal bore with an open forward end adapted to receive a male coupler, and a flow port for supplying pressurized fluid to the internal bore. A tubular spacer is inserted in the housing bore and forms therewith an outer flow passage isolated from an internal bore in the spacer. The spacer has an open forward end and a rear end wall closing the rear end of the spacer. A valve body, which is axially slidable in the spacer bore, includes a main cavity opening to the forward end of the housing bore and a peripheral inlet passage through the valve body communicating the outer flow passage with the main cavity. The valve body and the rear end wall of the spacer define therebetween a vent cavity; and the spacer has an annular land press-fitted in the housing bore and located axially between the outer flow passage and a vent chamber within the housing bore, which vent chamber communicates with the vent cavity via a passage in the spacer. The annular land has an annular groove retaining an annular seal for sealing against the side wall of the housing bore to prevent leakage flow from the outer flow passage to the vent chamber. The press-fitted land protects against extrusion of the seal between the spacer and the housing wall.
In a preferred embodiment, the housing has a rear end wall including a counterbore opening to the housing bore, and the rear end wall of the spacer has an axially rearwardly extending post press-fitted in the counterbore. The annular land and the post preferably are coaxial, and the post may include an annular groove retaining an annular seal for sealing against the housing which may include the flow port in a rear end wall thereof. As will be appreciated, the two-point press-fit securement of the spacer enables elimination of the prior art tubular extension of the end plug that is threaded into the end of the cylindrical portion of the housing opposite the flow port. Consequently the overall length and weight of the female coupler can be reduced if desired.
According to a further aspect of the invention, a female coupler, comprises a housing having an internal bore with an open forward end adapted to receive a male coupler, and a flow port for supplying pressurized fluid to the internal bore. A valve body is disposed in the bore and axially moveable in the housing. The valve body includes a main cavity opening to the forward end of the housing bore, a peripheral inlet passage through the valve body communicating with the main cavity, and an interior valve seat forwardly of the inlet passage. A piston is axially movable in the valve body and includes a central bore in which a poppet valve is slidably guided. The poppet includes a valve portion disposed in the main cavity of the valve body, a forward projection adapted to engage a check valve in the male coupler when the male coupler is received in the housing, and a rearward tubular portion radially stepped to form a annular shoulder portion joining a front wall section to a rear wall section. At least one coil spring is provided to forwardly bias the poppet valve against the valve seat to normally prevent fluid flow through the valve body. A forward portion of the coil spring is radially constrained by a radially inner surface of the front wall section of the rearward portion of the poppet valve, while the rear wall section has a radially inner surface spaced radially outwardly from the coil spring to form interiorly of the poppet valve a flow path for pressurized fluid passing form the main cavity to a back side of the piston. The annular shoulder portion includes one or more orifices for connecting the main cavity to the flow path without any interference of the coil spring.
According to yet another aspect of the invention, a female coupler comprises a housing having an internal bore with an open forward end adapted to receive a male coupler, a flow port for supplying pressurized fluid to the internal bore, and a locking collar chamber at the open forward end. A valve body, which is disposed in the bore and axially moveable in the housing, includes a main cavity opening to the forward end of the housing bore, and a peripheral inlet passage through the valve body communicating with the main cavity, and a tubular front end socket portion including at least one radial bore which retains a locking element for radially inward and outward movement. A locking collar is axially movable in the collar chamber between locking and release positions, the collar in its locking position being operative to hold the locking element at a locking position such that it protrudes radially inwardly of a radially inner surface of the socket portion for engaging a locking groove in the male coupler, and the collar in its release position enabling radial outward movement of the locking element for disengagement from the locking groove in the male coupler. A coil spring circumscribes the locking collar for biasing the locking collar against a stop, and an annular protection shield is interposed between a front end of the coil spring and a retainer at the front end of the locking collar chamber to hold the coil spring in the collar chamber. The protection shield has a radially inner edge adjacent and surrounding the socket portion of the valve body, thereby to prevent debris from entering the locking collar chamber.
Further features and advantages of the present invention will become apparent to those skilled in the art upon reviewing the following specification and attached drawings.